Push button device



Oct. 5, 1965 J. w. DORSEY 3,210,484

PUSH BUTTON DEVICE Filed April 20, 1962 INVEN TOR. John W. Dorsey.

Y FIG. 4 & z An 3 United States Patent 3,210,484 PUSH BUTTON DEVICE John W. Dorsey, Berkeley, Ill., assiguor to Automatic Electric Laboratories, Inc., Northlake, 11]., a corporation of Delaware Filed Apr. 20, 1962, Ser. No. 189,196 3 Claims. '(Cl. 200-5) This invention relates to a signalling device for transmitting a plurality of signals, and more particularly, to an improved construction for a push button-type signalling device which may be used, by way of example, in a telephone circuit such as disclosed in U.S. Patent 2,824,173, issued Feb. 18, 1958, by L. A. Meacha-m and assigned to Bell Telephone Laboratories.

Heretofore the above type of signalling device used a plurality of conventional make and break type contact springs which were arranged in a number of ways to accomplish a desired signalling mode. Furthermore, these devices required the relatively laborious operations of connecting wires to the contact springs and making the critical contact adjustments. The present invention eliminates the use of such contact springs which require contact adjustment and alignment operations. Moreover, it employs a printed circuit card to furnish the transmission paths in stead of using individual wires for this purpose.

The principal object of the invention is to provide a push button-type signalling device wherein the assembly operations are minimized and the critical assembly operations eliminated.

Another object of the invention is to provide a push button-type signalling device which utilizes printed circuit cards for the transmission paths.

Still another object of the invention is to provide a push button-type signalling device with is particularly adapted for use in a telephone.

Still another object of the invention is to provide a signalling device for transmitting a plurality of frequencies.

I-n fulfillment of these objectives the signalling device of the invention features in general a matrix of switch assemblies of the push button type; at least one printed circuit card which supplies the necessary electrical paths for the incoming and outgoing signals; a micro-switch which is connectable to the electrical paths, and an actuator plate which lies intermediate the ends of the switch assemblies and the micro-switch thereby serving as the means through which the former operates the latter. Each switch assembly employed, consists of a key member or a finger button; a plunger rod of varying diameter which is connected to the finger button and extends through; two pairs of washers, one pair thereof being lock washers which are positioned in specific grooves in the plunger rod, and the other pair thereof being conventional washers which lie adjacent to the lock washers; a contact spring made in the form of a washer and having three contact elements which are equally spaced on one surface thereof; and apair of tension springs which in combination serve to spring load and stabilize the switch assembly with respect to the other components of the device.

The contact springs in combination with the contact elements disposed thereon serve to bridge the pairs of conductor segments which are disposed on the printed circuit card. The bridging takes place when a finger button ice of the switch assembly is depressed by an operator thereby lowering the contact spring assembly against the conductor segments. The relative position of the contact springs with respect to the circuit card is such to provide a certain amount of over-travel of the plunger rod after the contact elements make contact with the conductor segments. This is to insure proper contact pressure. Also, the actuator plate is located below the ends of the switch assemblies so that the bridging of any one of the conductor segments is made before the micro-switch is effected. The microflswitch is operated by means of the actuator plate advancing against a sensing tab of the microswitch until it reaches the critical point, or the point of operation.

These and other objects and features will become more apparent from a perusal of the following detailed description taken wit-h the accompanying drawings of which:

FIG. 1 is a perspective view of the signalling device according to the invention as applied to a conventional telephone environment.

FIG. 2 is an exploded perspective view of a push button switch assembly used in the device.

FIG. 3 is a plan view of one arrangement of a printed circuit card used in the device.

FIG. 4 is a cross sectional view of the signalling device according to the invention taken substantially along the line 2-2 of FIG. 1.

Referring now to the drawings, FIG. 1 illustrates one use for the signalling device of the invention. In such an application it is necessary to provide a signalling scheme whereby a plurality of different electrical signals can be transmitted to central office telephone equipment and make a particular line connection between a calling party and a called party. Accordingly, when a signalling device is used in the circuit of the cited patent, for example, a different signal is produced by each switch assembly. This scheme then operates upon depressing in sequence a number of finger buttons 10 exposed on face plate 13 and assembled to telephone 11. The result is two fold: first, the transmission path associated with a particular switch assembly is completed by contact spring 27 bridging a particular pair of conductor segments 37 and 38; secondly, the actuator plate 25 is advanced against the sensing tab 23 of micro-switch 22 which throws the battery of the line, for example, over the transmission path created. Each transmission path thusly formed is in turn preferably associated with an identifying means which according to the cited patent is the combination of a magnetic core with a group of condensers. A similar scheme employing zener diodes or matched resistances can be used for this purpose equally as well however.

FIG. 2 represents one of the principal components of the device, the switch assembly. The frame structure for the switch assembly includes face plate 13, plate 34, circuit card 35 and spacers 16 and 17.

The switch assembly includes a plunger rod 26 which is preferably made of a brass material so that it can be made as a high production item on a screw machine for example. The rod is machined or formed so that one end has a relatively large diameter leaving a shoulder 40, the other end has cut away portions leaving but a substantially rectangular post 43 for insertion into a corresponding hole 44 in finger button 10. Intermediate the ends are two grooves 41 and 42 which receive lock it is manually depressed.

washers 30 and 33 respectively. Placed adjacent to the lockwashers are two additional washers 29 and 32 respectively. Butting against these latter washers are two coil springs 28 and 31. Spring 28 is placed over rod 26 and positioned between washer 29 and contact spring 27. Contact spring 27 is therefore spring loaded against the aforementioned shoulder 40. Spring 31 is placed between washer 32 and a cross member or plate 34, shown in FIG. 4. The two springs of the switch assembly then are placed on either side of plate 34. The result of this separation of the springs is that the switch assembly is stabilized with respect to the other components of the device and the plunger rod restores automatically after In addition, the contact spring is spring loaded through the coil springs 28 and 31.

As for contact spring 27 it is made of a spring material having good conductive properties, such as nickel-silver. Furthermore, its preferred shape simulates a conventional washer. To improve the sensitivity of the contact operation the contact springs each have three or more contact elements 36 which are preferably welded to one surface thereof. These elements are equally spaced on the contact spring so as to insure that the contact spring 27 makes contact with the conductor segments 37 and 38 on at least two places; that is, since the conductor segments are disposed on the circuit card 35 in pairs it is possible for one control to be between the segments. FIG. 3 shows the printed circuit card 35 which is made of a relatively sturdy insulating material, such as a plastic. The thickness of the card should be such to withstand the pressure exerted thereon by the depression of the switch assemblies by an operator. The circuit card includes four, for example, mounting holes 39. Furthermore it includes a layout of the aforementioned conductor segments 37 and 38 and termination pads 50. As can be seen in FIG. 3 the segments are grouped in pairs around a plurality of apertures 49. Therefore, at each aperture there is a different pair of conductor segments. Consequently since each pair is associated with a different condenser, for example, a different signal can emanate from the condenser with each switch assembly and produce a distinctive frequency response. This described external circuitry is made through termination post 50.

FIG. 4 shows the individual elements of the device in assembly. Three of the aforcdescribed switch assemblies are shown. The plunger rods of each extend through an aperture 14, of the cross member or face plate 13, an aperture of another cross member or more particularly plate 34, and an aperture 49 of the printed circuit card 35.

The apertures 14 are counterbored so as to accommodate the finger button 10. These counterbored apertures are just large enough to receive the finger buttons and just deep enough to allow them adequate movement for the switch assemblies to accomplish their two fold pur pose aforementioned. Plate 34 as aforementioned is used to separate the springs 28 and 31. Circuit card 35 is placed in a plane parallel to the planes of plates 13 and 34 with its conductor segments 37 and 38 projecting toward the contact elements 36 of the contact springs 27. There is suflicient clearance between the apertures and the plunger rods 26 extending therethrough so that operation of each switch assembly can be done smoothly and without difficulty.

Spaced from the free ends of the plunger rod 26 is a micro-switch 22. This switch is of the conventional type and has terminals 24, which are connectable to external circuitry, and a sensing tab 23. Assembled adjacent to the tab 23 is an actuator plate 25, preferably made of a durable plastic so as to withstand the pressure of the plunger rods and still operate quietly when being contacted by the rods 26. The micro-switch is mounted to the rest of the components by screws 40 extending through holes in its flange 21. The screws extend furthermore through corresponding holes in mounting plate 20, circuit card 35, plate 34, and into tap holes 47 of face plate 13. Separating or spacing the cross members, that is the aforementioned plates, and the printed circuit cards is accomplished by four sets of spacers 1619. One set of spacers 16 lies between face plate 13 and plate 34, another set of spacers 17 lies between plate 34 and circuit card 35, another set of spacers 18 lies between mounting plate 20 and circuit card 35, and still another set of spacers 19 lies between flange 21 of the micro-switch 22 and mounting plate 20. This assembly can be completed in very little time and with very few operations, none of which are considered to be of a critical nature. Moreover, the assembly is a unit which is easily mountable.

The construction of the device just described employs a minimum number of parts. The parts can be made on a high production basis and thus manufacturing cost of the device can be kept at a minimum. Also in this connection it is to be emphasized that the particular contact springs employed in the device do not require any adjustment or alignment.

One embodiment of the invention has been described in detail, however, it is to be understood that this was done merely by way of example and not as a limitation to the spirit and scope of the invention as hereinafter claimed.

What is claimed is:

1. A signalling device for transmitting electrical signals comprising: a supporting structure; at least one directacting switch assembly having a central axis and supported by said frame structure and comprising: a plunger rod having an upper end and also a lower end with an abruptly enlarged diameter, a finger button secured to said upper end of said plunger rod, and at least one circular contact spring having at least three contact portions and an aperture permitting said contact spring to float adjacent to said abruptly enlarged diameter of said plunger rod, said plunger rod extending from said finger button through said contact spring aperture; a printed circuit card mounted by said frame structure and lying in a plane normal to said central axis of said switch assembly and including an aperture through which said plunger rod extends, and also including at least one pair of conductor segments positioned about said last-mentioned aperture and in operative relation to said contact spring, said pair of conductor segments being contacted by said floating spring contact portions in response to depressing said plunger; and a micro-switch secured to said frame structure and means whereby said micro switch operates in response to depressing said plunger rod.

2. A signalling device for transmitting electrical signals comprising: an insulating card having apertures therein and carrying a printed circuit which includes pairs of printed conductor branches positioned about said apertures;

direct acting switch assemblies each having: a depressible plunger rod extending within a corresponding one of said apertures, a finger button secured to one end of said rod, and a floating contact spring carried by said plunger rod and having three contact portions, said contact portions being engageable with a corresponding one of said pairs of printed conductor branches and positioned to insure electrical continuity therebetween, and means whereby at least two of said contact portions are moved into engagement with said pair of printed conductor branches thereby completing a continuous electrical path. 3. A signalling device for transmitting electrical signals as claimed in claim 2 wherein said contact spring includes furthermore a substantially flat washer-shaped member with an aperture therein which receives said plunger rod and which has a top and bottom surface,

said three contact portions being fixed to said bottom surface and extending outwardly therefrom.

References Cited by the Examiner UNITED STATES PATENTS 6 3,050,605 8/62 Pollak 200-168 3,080,457 3/63 Jansson 200-5 3,120,583 2/ 64 Cornell 200-5 FOREIGN PATENTS 1,282,035 12/61 France.

164,7 86 9/58 Sweden.

KATHLEEN H. CLAFFY, Primary Examiner. BERNARD A. GILHEANY, Examiner. 

2. A SINGNALLING DEVICE FOR TRANSMITTING ELECTRICAL SIGNALS COMPRISING: AN INSULATING CARD HAVING APERTURES THEREIN AND CARRYING A PRINTED CIRCUIT WHICH INCLUDES PAIRS OF PRINTED CONDUCTOR BRANCHES POSITIONED ABOUT SAID APERTURES; DIRECTED ACTING SWITCH ASSEMBLIES EACH HAVING: A DEPRESSIBLE PLUNGER ROD EXTENDING WITHIN A COREESPONDING ONE OF SAID APERATURES, A FINGER BUTTON SECURED TO ONE END OF SAID ROD, AND FLOATING CONTACT SPRING CARRIED BY SAID PLUNGER ROD AND HAVING THREE CONTACT PORTIONS, SAID CONTACT PORTIONS BEING ENGAGEABLE WITH A CORRESPONDING ONE OF SAID PAIRS OF PRINTED CONDUCTOR BRANCHES AND POSITIONED TO INSURE ELECTRI- 